When you find a target of where you want to cast always check the path of your back cast. You usually need just as much room for your back cast as your forward cast. Are there branches you might hook? Sometimes you can find a hole between the branches and get a tight loop through there during your back cast. If you can't do that move to a position so nothing is impeding your back cast. The next thing is following through on your cast after it has hit the water. I can't tell you how many times I've seen someone cast off target and instead of following through on the drift they rip the fly out of the water and recast. I don't know about you but I have never found a way to rip a fly half way through a drift without making a sound. Many times there's a bloop sound or a noise that is anything but natural. If a fish is in sight you might get away with this once but definitely not twice. Even if the fish happens to not spook it definitely knows something isn't right.
To Wade or Not to Wade
Let's say you see a fish from shore and it seems that it hasn't seen you yet. You could cast to the fish from your location but if you could get in the water you'd be able to cast to the fish easily. What do you do? At the last fly show there was a seminar by Ossie Ozefovich. The talk was about how trout see underwater. Ozzie has done a ton of research on how trout react to fishermen. During his talk he explained that most fish see two ways. They have a monocular view from the side and a binocular view from the front. A light bulb went off when he went over this. I have always wondered why fish in high traffic areas never seemed to spook. There is a pond near where I live that has a nice population of bass. These bass can be seen from shore but they would spook once you stopped to look at them. I thought about it more and realized the bass saw people running or walking by and from their monocular view they could never tell how far away people were. If someone stopped to look at them that wasn't normal so the fish would turn to face the person on shore. This would give the fish a binocular view and they could judge the distance. Imagine if you saw a giant in your peripheral then turned so it was facing you. Once you turn the giant seems to be within feet of you. You'd spook right? Same with a a fish. If you see a fish and think you can get in the water and approach it without spooking it go for it. I think for the average fisherman this is too difficult a task, you'd be better off walking a head of the fish or standing far behind and making a cast.
When wading calm water you need to manage the wake you make when wading. In calm wader every movement you make sends out a ripple. This can spook any fish that's leary. I never believed in this theory much until I fished The Smith River in VA. The river has many calm sections that almost look like glass on the surface. It's not uncommon to see fish rising but you'll notice the fish fairly rise close to where you're wading. I did my best to make as little wake and ripples as possible. No matter what I did the rises were always just at the edge of where my ripple receded and blended into the glass calm water. The fish obviously associated ripples with danger. I had to make sure I waded as slow as possible and try not to disturb the water as well as the rocks beneath my feet. Try this the next time you're in a swimming pool. Usually by the steps entering the pool there is a metal handrail that leads down the steps into the water. Have someone take a key or something metal and stand near the rail. Go to the deep end and go under water. While under water have someone tap the rail with the key. You can usually hear the tapping from the other side of the pool. Now imagine how the five rocks under your feet grinding together sound as you're wading. In fast water with the other ambient noise you can probably get away with it. In calm slow water it's tough.
Fish Associate Disturbance With Danger
A fish needs to feel safe to give you the best chance at catching it. I believe if a fish is comfortable it will feed even if your fly doesn't match the food sources or your presentation isn't the greatest. The fish will hit the fly out of curiosity if nothing else. Think about how you're going to disturb the water before you fish, I grantee your hook up rates will increase.